This invention relates generally to gas turbine engines, and more particularly to apparatus and methods for sealing turbine shrouds in such engines.
A typical gas turbine engine includes a turbomachinery core having a compressor, a combustor, and a turbine in serial flow relationship. The core is operable in a known manner to generate a primary gas flow. The turbine includes one or more rotors which extract energy from the primary gas flow. Each rotor comprises an annular array of blades or buckets carried by a rotating disk. The flowpath through the rotor is defined in part by a shroud, which is a stationary structure which circumscribes the tips of the blades or buckets. These components operate in an extremely high temperature environment, and must be cooled by air flow to ensure adequate service life. Typically, the air used for cooling is extracted (bled) from the compressor. Bleed air usage negatively impacts specific fuel consumption (“SFC”) and should generally be minimized
The turbine shroud typically comprises a ring or array of side-by-side arcuate segments. Leakage between adjacent segments must be minimized in order to meet engine performance requirements while providing adequate cooling to the hardware. This is often accomplished using spline seals which are small metallic strips that bridge the gaps between adjacent shroud segments. Multiple spline seals are often positioned in axial and radial directions, in intersecting slots. In order to reduce leakage at the interface of two perpendicular seals, a seal with an L-shape (an “L-seal”) is sometimes used in order to dead-end chute flow in the seal slots. The L-seals are small and not easily assembled, and increase the number of parts needed for the shroud assembly.
Accordingly, there is a need for a spline seal which prevents leakage at the intersection of shroud seal slots and which is easy to assemble.